I don't think this is much of a problem. None of the decentralized exchanges have much volume currently. It's apparent that the market prefers centralized exchanges at this point.
Then the market is an idiot, because centralized exchanges defeat the whole point of blockchain: that the ledger is public and transparent. That means those parts where the ledger is private and opaque, there is a high risk of manipulation, such as self-trading and fake buy and sell walls.
Therefore I am quite skeptical there can be such a thing as a good hybrid exchange. Because if some transactions cannot be traced, all decentralized transactions connected to those untraceable transactions cannot be fully traced. Thereby a hybrid exchange marries the disadvantages of decentralization (slow, hard to scale, frontrunning) with the disadvantages of centralization (single point of failure, need to trust the institute not to commit fraud, KYC/AML).
Well, fake buy and sell walls plus wash trading are a thing in decentralized exchange too. I see only a couple exchanges where you can't do that, Bancor and Flip.me (I don't know BarterDEX since i never used it)